dbench -t 300 -D $mpoint --clients-per-process=4 16 | tail -19 >>
$log_file
mkdir $mpoint/bonnie
chown nobody.nobody $mpoint/bonnie
bonnie++ -u nobody:nobody -d $mpoint/bonnie -f -m
RAID${lvl}-${num}Disk-${chunk}k -n 64:65536:1024:16 >>$log_file
2>/dev/null
tiotest -f 1024 -t 6 -r 1000 -d $mpoint -b 4096 >> $log_file
tiotest -f 1024 -t 6 -r 1000 -d $mpoint -b 16384 >> $log_file

Obviously, I pulled these tests out of a script I use where all these
various variables are defined.  Just replace the variables with
something sensible for accessing your array, run them, save off the
results, run again with a different chunk size, then please post the
results back here as I imagine they would be very informative.
Especially the dbench results as I think they are likely to benefit the
most from the change.  Note: dbench, bonnie++, and tiotest should all be
available in the debian repos.

	I could not find tiotest.  Also, the version dbench in the distro
does not support the --clients-per-process switch.  I'll post the results
from the backup system here, and from the primary system in the next post.

Backup with bitmap-chunk 65M:

  16    363285   109.22 MB/sec  execute 286 sec
  16    364067   109.05 MB/sec  execute 287 sec
  16    365960   109.26 MB/sec  execute 288 sec
  16    366880   109.13 MB/sec  execute 289 sec
  16    368850   109.35 MB/sec  execute 290 sec
  16    370444   109.45 MB/sec  execute 291 sec
  16    372360   109.64 MB/sec  execute 292 sec
  16    373973   109.74 MB/sec  execute 293 sec
  16    374821   109.61 MB/sec  execute 294 sec
  16    376967   109.88 MB/sec  execute 295 sec
  16    377813   109.77 MB/sec  execute 296 sec
  16    379422   109.87 MB/sec  execute 297 sec
  16    381197   110.05 MB/sec  execute 298 sec
  16    382029   109.92 MB/sec  execute 299 sec
  16    383868   110.10 MB/sec  cleanup 300 sec
  16    383868   109.74 MB/sec  cleanup 301 sec
  16    383868   109.37 MB/sec  cleanup 302 sec

Throughput 110.101 MB/sec 16 procs
Version 1.03d       ------Sequential Output------ --Sequential Input-
--Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec
%CP
RAID5-7Disk-6 3520M           66779  23 46588  22           127821  29 334.7
2
                    ------Sequential Create------ --------Random
Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files:max:min        /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec
%CP
   64:65536:1024/16    35   1   113   2   404   9    36   1    54   1   193
5


Backup with default (2048K) bitmap-chunk


  16    306080    91.68 MB/sec  execute 286 sec
  16    307214    91.69 MB/sec  execute 287 sec
  16    307922    91.61 MB/sec  execute 288 sec
  16    308828    91.53 MB/sec  execute 289 sec
  16    310653    91.78 MB/sec  execute 290 sec
  16    311926    91.82 MB/sec  execute 291 sec
  16    313569    92.01 MB/sec  execute 292 sec
  16    314478    91.96 MB/sec  execute 293 sec
  16    315578    91.99 MB/sec  execute 294 sec
  16    317416    92.18 MB/sec  execute 295 sec
  16    318576    92.25 MB/sec  execute 296 sec
  16    320391    92.39 MB/sec  execute 297 sec
  16    321309    92.40 MB/sec  execute 298 sec
  16    322461    92.42 MB/sec  execute 299 sec
  16    324486    92.70 MB/sec  cleanup 300 sec
  16    324486    92.39 MB/sec  cleanup 301 sec
  16    324486    92.17 MB/sec  cleanup 302 sec

Throughput 92.6969 MB/sec 16 procs
Version 1.03d       ------Sequential Output------ --Sequential Input-
--Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec
%CP
RAID5-7Disk-2 3520M           38751  14 31738  15           114481  28 279.0
1
                    ------Sequential Create------ --------Random
Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files:max:min        /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec
%CP
   64:65536:1024/16    30   1   104   2   340   8    30   1    64   1   160
4